A First Measurement of the Coherent Elastic Neutrino-Nucleus Scattering Cross Section

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Precise experimental tests of fundamental particle properties are now a well-established way to search for new laws of nature beyond our current physical knowledge. The Standard Model of particle interactions describes known fundamental particles and their interactions. However, the Standard Model in its simplest form does not include a nonzero mass of the neutrino, for which there is now experimental proof. This calls for a continued effort to improve the Standard Model, and to further our knowledge of neutrino properties and interactions. Neutrino scattering from the nucleus, which leaves the nucleus intact, was first described some forty years ago, but still lacks an experimental demonstration. An accurate measurement of this mode of neutrino interaction, as planned here, will provide a handle on several still unconstrained neutrino properties, contributing information that helps to formulate refinements to the Standard Model.This research will use sodium-doped cesium iodide scintillators as an advantageous target for the detection of Coherent Elastic Neutrino-Nucleus Scattering, exploiting the intense neutrino yield from the Spallation Neutron Source facility at Oak Ridge National Laboratory. The response of this material to low-energy nuclear recoils, like those expected from this process, has been characterized and a full feasibility test has been performed using a 2 kg low-background prototype crystal in a dedicated radiation shield. Based on these studies, a planned 14 kg detector is expected to measure approximately 550 events per year from this mode of neutrino interaction. The still unmeasured neutron-generating charged-current neutrino interaction on Pb-208, of interest in nuclear physics and for supernova detection, will also be studied during the period of the award.